Loud speaker assembly



Aug. 23, 1960 c. A. PERRY LOUD SPEAKER ASSEMBLY Filed 001;. l, 1956ZNVENTOR. CHARLES A. PERRY ,4 TT'ORNEYS ilnited States Patent LOUDSPEAKER ASSEMBLY Charles A. Perry, Cieveland, Ohio, assignor to The RolaCompany, Inc, (Ileveland, Ohio, a corporation of Uhio Filed Oct. 1,1956, Ser. No. 613,187

2 Claims. (Cl. 179-1155) This invention relates to an improved andsimplified construction and method for assembling and mounting apermanent magnet field structure on the diaphragm housing of aloud-speaker.

Loud-speaker assemblies usually include a diaphragm supporting structurein the form of a housing and a magnetic field structure for energizingthe diaphragm voice coil. In a permanent magnet type loud-speaker, thefield structure may include a yoke, a magnet mounted thereon, a poletip, a front plate and some arrangement for protecting the air gap fromthe accumulation of foreign particles. An inherent problem in theconstruction and assembly of permanent magnet type loud-speakers is theexcessive labor and cost involved in the multiple handling of thecomponent parts. There are also additional supplemental operationsrequired to adjust the magnet and to insure that the diaphragm voicecoil is properly centered in the air gap formed by the field structure.

It is a principal object of this invention to provide a simplified andimproved construction and method for assembling and mounting a permanentmagnet field structure on the diaphragm housing of a loud-speakerwithout the need for cement, soldering or threaded fasteners of anykind.

A further object of this invention relates to the 'provision of animproved construction and method of as.- sembling and mounting apermanent magnet field structure on the diaphragm housing of aloud-speaker which automatically and permanently centers the pole tip inthe air gap during such assembly and mounting.

Briefly, the foregoing objectives are attained in accordance with thisinvention by providing a U-shaped yoke with projecting guides that areadapted to pass through properly located apertures in a front platewhich are in turn aligned with similarly located apertures on adiaphragm supporting housing. The diaphragm housing and front plateinclude central bores for receiving the voice coil which are adapted tobe axially aligned by virtue of the alignment of the foregoing apertureson the projecting guides. The front plate has projecting pins spacedcircumferentially about the central bore on its rear face which areadapted to engage similarly located apertures on a mating flange of amagnet centering member. The centering member is made of non-magneticresiliently flexible material and is cupshaped with a depressed centralportion that is adapted to overlie the central bore in the front platewhen mounted thereon. The front plate and centering member are firstassembled as a sub-assembly by staking them together and at the sametime piercing a bore through the depressed portion of the centeringmember which will be concentric with the bore in the front plate so thata core tip projecting through the centering member bore will beconcentric with the front plate bore. This is accomplished by pilotingthe piercing operation through the bore in the front plate. A permanentmagnet is supported within the yoke with its projected axis extendingthrough the concentric bores and a pole tip is mounted on the projectedextremity of the magnet and secured in centered position within theconcentric bores by means of the non-magnetic centering member. Theyoke, magnet, pole tip and the centering member and front platesub-assembly are then assembled on the diaphragm housing with the yokeguides extending through the apertures in the front plate and diaphragmhousing. Pressure is then applied to deform the projecting extremitiesof the guides and thereby fasten the component parts together. The depthof the depressed portion of the centering member is such that thepressure will collapse the depressed portion slightly and the resiliencyof the centering member will hold the pole tip in centered relationwithin the front plate bore.

In the drawings:

Fig. 1 is a side elevation of a loud-speaker having the field structurepartially cut away to illustrate the interior;

Fig. 2 is an exploded perspective view of the subassembly of a frontplate and core tip dust cup at an intermediate stage of assembly;

Fig. 3 is an exploded perspective view of the field structure inrelation to the diaphragm housing; and

Fig. 4 is an enlarged sectional view of the centering portion of theassembly.

Referring now more particularly to Figs. 1 and 3 of the drawings, thereis shown a preferred form of the loud-speaker assembly of this inventionhaving a permanent magnetic field structure which includes a yoke,indicated generally at It), which is formed from a metal blank bent inthe form of an open U-frame having a back plate 11 and sides 12 and 13.The field structure also includes a magnet 15, and a pole tip 16 and asub-assembly which includes a front plate 18 and a centering member 19which is fastened thereto by projecting nubbins 32.

The sides 12 and 13 of the yoke 10 are provided with outwardlyprojecting tangs 21 and 22 at their extremities so devised as to projectthrough spaced apertures 23 and 24 respectively in the front plate 18and subsequently through similarly located apertures 26 and 27 in therear of the diaphragm housing 20. The apertures in the front plate anddiaphragm housing are located so that when they are aligned with eachother along the tangs 21 and 22, the housing 17 will be aligned axiallywith a central bore 28 in the front plate 18. The magnet 15 is supportedon the back plate 11 of the yoke and in turn is extended axially by thepole tip 15 which extends through axially aligned bores 29, 28 and 17 inthe centering member 19, the front plate 18 and diaphragm housing 20 insuch manner as to define a concentric air gap surrounding the pole tip,which is adapted to receive in centered relation a voice coil 36 carriedby the throat of the diaphragm.

Referring now more particularly to Fig. 2 of the drawings, the frontplate 18 and centering member 19 are shown dis-assembled in the explodedview to expose the projecting nubbins 32 on the rear face of the frontplate, which are spaced from each other circumferentially about thecentral bore 28. The centering member 19 is composed of a resilientlyflexible and non-magnetic cup-shaped member having a planular flangedportion 33 with apertures 34 through the respective corners forreceiving the nubbin-like projections 32 on the rear face of the frontplate. The central portion 35 of the centering member is depressed toform a dust cup which is adapted when assembled to surround the pole tip16. In the preferred form shown, the centering member is staked to thefront plate 18 and the depressed dust cup portion 35 is pierced by asuitable die which is piloted through the bore 28 in the front plate 18to make the bore 29 concentric with the bore 28. In assembly the bore29, which is of substantially the same or slightly greater diameter thanthat of the pole tip 16, automatically guides the pole tip into centeredrelationship and is maintained fixed without fear of distortion frombumps that normally occur in the rough handling incident to the packingand a of a press. The magnet 15 is then located in a slight recess 36which is provided on, the inner face of the back plate 11 to insure thatthe magnet will not slide'out of the yoke. The pole tip 16, which isprovided with a flange 37 on one extremity, is inserted into the bore ofthe centering member 19, and the pole tip and sub-as sembly of the frontplate 18 and centering member 19 are then placed as a unit upon the yokewith the fangs 21a nd 22 projecting through apertures 23 and 24 in thefront: plate 18. This 'operatesto position the magnet,

and pole tip 16 in centered alignment and at the same time brings theflanged end '37 of the pole tip into abutting engagement against theadjacent end of the magnet. 3 r j Thereafter, the diaphragm housing 2.0is placed over the front plate 18 with the apertures 26 and 27 inregistration with the apertures 23 and 24, at which time the tangs 21and 22 project through the apertures. While the assembly 'is so held onthe stationary head of the press, the movable head of the press isbrought down so as to swage the tan'gs 21 and 22 against the front faceof the diaphragm housing 20. The depth of the central depressedportion135 of the centering member 19 is such that the press initiallycollapses the portion 35 slightly against the flange 37 and causes thewall of the portion 35 to deform inwardly to insure a tightly centeredassembly of the component parts. The position of the portion 35 beforeand after the application of pressure by the press is illustrated in Fig4 of the drawings, wherein the broken line represents the positionbefore deformation and the full linerepresents the position afterdeformation. Further pressure from the press following the collapsing ofthe central portion 35 swages the tangs 21 and22 against the front faceof the diaphragm housing to permanently secure, the component partstogether in centered relation. It will be readily apparent that theautomatic and permanent centering which results from the construction'and method of assembly hereinbefore described eliminates the necessityfor the use of centering gauges and also reduces the number of parts andmajor handling operations as well as those additional supplementaloperations ordinarilymequired to center the core tip and voicecoilwithin the air gap. 1 e

I have shown and described'what I consider to be the preferredembodiment of my invention along with suggested modified forms, and itwill be obvious to those skilled in the art that other changes andmodifications may be made both in the construction and in the method ofassembly ofthe loud speaker Without departing from the scope of myinvention as defined by the appended claims. V f

I claim: r V a 1. A permanent magnet loud speaker assembly comprising incombination, a diaphragm housing having a a central bore for receiving adiaphragm voice coil, a magnetic structure including a yoke and a magnetand a pole tip, saidpole tip having ,a'flanged extremity adapted havinga depressed central portion overlying and extending axially away fromthe central bore in said front plate, said depressed central portionhaving a radially disposed and inwardly directed marginal flangedefining a pole tip receiving bore therethrough, means on said frontplate coacting with complementary means on said flexible member formaintaining said pole tip receiving bore concentric with said centralborein said front plate, the size and configuration of said pole tipreceiving here being substantially'the same as" the cross-sectionalconfiguration of said pole tip to guide andhold the pole tip in centeredrelation within the air gap, said depressed central portion of saidflexible member having an axial extent sufficient to coact undercompression between the front plate and the pole tip flange and exert anaxial force against said magnet for maintaining said pole tip, magnetand yoke in operative assembled relation, and means on said yoke formedintegrally therewith and coacting with complementary means on'saidfrontplate and with complementary means on said diaphragm housing to compresssaid flexiblemember and hold said magnetic structure inoperative'assembled relation with said housing. H Q M 2. A permanentmagnet loudspeaker assembly comprising in combination, a diaphragmhousing having a central bore for receiving a diaphragm voice coiltherethrough, a magnetic field structure having an open ended yokesupporting a magnet thereon, a pole tip having to ,seat'against anadjacent axial extremity of the magnet when assembled, a front platedetachably mounted on said yoke for mounting the magneticstructure onthe diaphragm housing, said front plate having'a central bore formingan, air gap concentrically surrounding said pole tip, means forautomatically centering said pole tip in concentric relation in saidcentral bore of said front plate, said means including aresiliently'flexible member an annular flange thereon, said pole tipbeing supported in axially aligned relation within said yoke and on saidmagnet and projecting toward the open end of said yoke, a front platefor coupling the open end of the yoke to the diaphragm housing inoperative relation to a diaphragm voice coil, said front plate having abore sur rounding the'pole tip and providing an air gap therebetween forthe voice coil, a non-magnetic centering member carried .by the frontplate and having a central bore concentric and axially aligned with thefront plate bore, projections on the rearward face of said front platereceived in complementary openings in said centering member forsupporting said centering member in proper position on'said'front plate,the size and configuration of said pole tip and saidcentering memberbore being substantially the same to maintain the" tip in fixed'centered relation in the front-plate bore, said centering memher beingformed of resilient-like material and having a cup-like centraldepression with said centering member here extending therethrough, thewalls of said cup-like depression having an "axial extent suflicient tocoact :under compression between said'pole tip flange and said plate tohold'said pole tip, said'magnet, a'ndsaid. yoke inoperativeassembledrelation, said diaphragm housing and said front plate each having aplurality of complementary apertures spaced'similarly about theirrespective bores with the corresponding apertures in said front plateand said diaphragm housing being axially aligned, andspaced deformableprojections on the open end of said yoke'formed complementally to therespective of said apertures and projecting through respective alignedpairs of said apertures in said front plate and diaphragm housing, thefree ends of said projections on said yoke being deformed against thefront face of said diaphragm housing for securing all of the componentsof the field structure together onthe diaphragm housing, with the poletip positively held in centered relation in the air gap.

, References Cited in the file of this patent UNITED STATES'PATENTS'France Nov. 29, 1948

